This blog provides short, easy-to-digest summaries of recently published research relating to bullying, peer-aggression and peer-victimization. It is maintained by staff and students from the School of Psychological Sciences and Health at the University of Strathclyde.

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June 16, 2011

Victims of bullying twice as likely to be depressed later in life.

Ttofi, M.M., Farrington, D.P., Lösel, F., & Loeber, R. (2011). Do the victims of school bullies tend to become depressed in later life? A systematic review and meta-analysis of longitudinal studies. Journal of Aggression, Conflict and Peace Research, 3 (2), 63-73.

These authors conducted a review of longitudinal studies which have examined the relationships between victimization in childhood and depression in later life. Longitudinal studies are those which collect data at one point in time (e.g. whether a child is bullied or not) and then collect more data again at a much later point in time (e.g. levels of depression in adult life). These kinds of studies are considered to provide strong evidence for the presence or absence of bullying as something which causes later depression. It is also possible to control for other possible causes of later depression to see whether being bullied can increase levels of depression in addition to other risk factors.

The authors also conducted a meta-analysis. This means they conducted statistical analyses on data from a number of published and unpublished studies. Meta-analyses are considered to provide more reliable judgements about the relationships between behaviours of interest (e.g. being bullied and feeling depressed) than individual studies because they pool information across different studies using different measures, samples, times, and places.

Results suggest that victims of bullying are twice as likely as non-victims to experience later depression. After controlling for other causes of later depression, this reduced slightly but being bullied remained an important predictor of later depression. The authors note that their results indicate that 33% of bullied children reported later depression as compared to 22% of other children. This is a 50% increase in risk of developing later depression.

The authors conclude that there is reliable research evidence which supports the importance of anti-bullying interventions. Reducing levels of bullying helps individuals to live happier lives, but at the same time society benefits financially because of the associated savings in health care and welfare.